The Bucket Pump is similar to the Rag
Pump and Lift Disk Pump but does not
require a tube to draw the water up. It is not very common anymore, but can still
be found occasionally. One advantage of this pump is that the buckets don't
turn upright until they are well below the surface of the water. They fill with
clean water, and bring up less of the scum that often floats on the surface of
a well.
Large old sailing ships sometimes used Bucket Pumps. They were also
used on farms and many other places.
Of course, the length of the chain and
the number of buckets can vary greatly.
(This is a still representation and possibly also a low-resolution
image of a fully animated pump.) 
